Method and apparatus for forming backside die planar devices and saw filter

1. An apparatus comprising:

a backside of a first die having a redistribution layer (RDL);

one or more passive planar devices on the backside, the one or more passive planar devices formed in the RDL;

a front-side of the first die having an active region;

one or more vias to couple the active region with the one or more passive planar devices, wherein the one or more vias include ground and signal vias; and

a layer comprising piezoelectric material, wherein the layer is on the backside of the first die such that the layer is disposed on the RDL.

2. The apparatus of claim 1 comprises a second die coupled to the backside of the first die.

3. The apparatus of claim 2 , wherein the second die includes an active region coupled to the one or more passive planar devices of the first die.

4. The apparatus of claim 1 comprises a passivation layer on the layer.

5. The apparatus of claim 1 , wherein the one or more passive planar devices is one or more of:

a SAW filter;

a band-pass filter;

a low-pass filter;

a high-pass filter;

an inductor;

an antenna; or

a balun.

6. The apparatus of claim 1 comprises bumps on the backside of the die to couple the one or more passive planar devices to another die.

7. An apparatus comprising:

a backside of a die having a redistribution layer (RDL);

one or more SAW filters on the backside, the one or more SAW filters in the RDL;

a piezoelectric layer on the RDL over the one or more SAW filters;

a front-side of the die having an active region; and

one or more vias to couple the active region with the one or more SAW filters.

8. The apparatus of claim 7 , wherein the active region comprises a low noise amplifier (LNA) coupled to one of the one or more SAW filters.

9. The apparatus of claim 7 , wherein the active region comprises a power amplifier (PA) coupled to one of the one or more SAW filters.

10. The apparatus of claim 7 further comprises one or more passive planar devices on the backside.

11. A system comprising:

a memory;

a processor die coupled to the memory, the processor die having:

a backside with a redistribution layer (RDL);

one or more passive planar devices on the backside, the one or more passive planar devices formed in the RDL;

a front-side of the first die having an active region; and

one or more vias to couple the active region with the one or more passive planar device;

a layer comprising piezoelectric material, wherein the layer is on the backside of the first die such that the layer is on the RDL; and

a wireless interface to allow the processor to communicatively couple with another device.

12. The system of claim 11 comprises a display interface for displaying content processed by the processor.

13. The system of claim 11 , wherein the active region comprises a low noise amplifier (LNA) coupled to one of the one or more passive planar devices.

14. The system of claim 13 , wherein the one or more vias include ground and signal vias.

15. The system of claim 11 comprises another die coupled to the backside of the processor die.